Apparatus for advanced packaging applications

ABSTRACT

The embodiments disclosed herein pertain to novel methods and apparatus for removing material from a substrate. In certain embodiments, the method and apparatus are used to remove negative photoresist, though the disclosed techniques may be implemented to remove a variety of materials. In practicing the disclosed embodiments, a stripping solution may be introduced from an inlet to an internal manifold, sometimes referred to as a cross flow manifold. The solution flows laterally through a relatively narrow cavity between the substrate and the base plate. Fluid exits the narrow cavity at an outlet, which is positioned on the other side of the substrate, opposite the inlet and internal manifold. The substrate spins while in contact with the stripping solution to achieve a more uniform flow over the face of the substrate. In some embodiments, the base plate includes protuberances which operate to increase the flow rate (and thereby increase the local Re) near the face of the substrate.

BACKGROUND

Photoresist is a light sensitive material used in certain fabricationprocesses to form a patterned coating on a work piece, e.g., asemiconductor wafer, during processing. After exposing the photoresistcoated surface to a pattern of high energy radiation, a portion of thephotoresist is removed to reveal the surface below, leaving the rest ofthe surface protected. Semiconductor processes such as deposition,etching, and other processes may then be performed on the partiallyuncovered surface and remaining photoresist. After performing one ormore semiconductor processes, the remaining photoresist can be removedin a strip operation.

Both negative and positive photoresists may be used to pattern a wafer.With positive photoresist, exposure to the high energy radiation causesthe resist material to become more soluble in the developer, as comparedto parts of the resist that are not exposed to the radiation. As such,when a substrate patterned with positive photoresist is exposed todeveloper, the areas where the resist was exposed to radiation areremoved, while the resist in non-exposed areas remains intact. Negativephotoresists work in the opposite manner, in that exposure of a negativephotoresist to high energy radiation causes the negative photoresistmaterial to become less soluble in developer. Therefore, after contactwith the developer, the areas of the negative resist that were exposedto radiation remain intact, while areas of the resist that were notexposed are removed.

One area in which negative photoresists have been adopted for use is inWafer Level Packaging (WLP) processes such as in bump and copper pillarapplications. For example, these processes may utilize certain negativedry film and spin-on photoresists. These materials have provenespecially advantageous in these applications because they have goodadhesion to substrates, excellent compatibility with platingchemistries, and result in well-formed, vertical profiles withessentially no footing at the feature base, even for deep features(e.g., features deeper than about 20 μm). Negative photoresists presentcertain fabrication problems, however. One main issue with the use ofthese materials is that negative photoresists are quite difficult toremove.

SUMMARY

Certain embodiments herein relate to methods and apparatus for removingmaterial from a substrate. In some cases, the material removed is anegative photoresist material, and the substrate is a partiallyfabricated semiconductor substrate, though the embodiments are not solimited.

In one aspect of the embodiments herein, a method is provided forremoving material from a substrate. The method includes (a) receiving asubstrate having material for removal thereon; (b) positioning andsealing the substrate in a substrate holder such that the material forremoval is exposed; (c) positioning the substrate holder in a removalposition, thereby forming a cavity defined on one side by the substrate,defined on the opposite side by a base plate, and defined around theedges by a flow distributor, where the cavity has a dimension betweenabout 2-10 mm as measured in a direction perpendicular to a face of thesubstrate, and where the flow distributor includes (i) an internalmanifold spanning between about 90-180° around the flow distributor,where the internal manifold is a cavity in the flow distributor throughwhich fluid may flow, and (ii) one or more inlets for delivering fluidfrom one or more fluid supply lines to the internal manifold and (iii)an outlet manifold spanning between about 90-180° around the flowdistributor, and positioned opposite the internal manifold; (d) rotatingthe substrate in the substrate holder; and (e) flowing strippingsolution from the one or more inlets, through the internal manifold,into the cavity over the face of the substrate, and out through theoutlet manifold, to thereby remove from the substrate at least some ofthe material for removal.

In various embodiments, sealing the substrate in the substrate holderforms a fluid tight seal between the substrate and substrate holder. Themethod may also include positioning the substrate holder in an openposition such that the substrate may be removed from the substrateholder, and removing the substrate. In some cases, the material forremoval includes photoresist material. The photoresist material may be anegative photoresist material. In some implementations, the strippingsolution is flowed at a rate between about 20-40 LPM. The strippingsolution may include a DMSO- and/or TMAH-based solution in some cases.In various embodiments, the substrate to be treated has featuresthereon, and the features may have a principal dimension between about5-120 μm. In some cases, the material for removal is completely removed.In other cases, it is substantially completely removed. In oneimplementation, the material for removal is substantially completelyremoved within about 4 minutes after beginning to flow strippingsolution over the face of the substrate.

In another aspect of the embodiments herein, an apparatus for removingmaterial from a substrate is provided. The apparatus may include aremoval cell including (a) a substrate holder configured to hold androtate a disc-shaped substrate in a substrate plane, (b) a base platepositioned substantially parallel to the substrate plane such that acavity is formed between the base plate and the substrate when thesubstrate is present in the substrate holder, where the distance betweenthe base plate and the substrate in the substrate holder is betweenabout 2-10 mm, and (c) a flow distributor at least partially positionedbetween the baseplate and substrate holder, where the flow distributorincludes (i) an internal manifold spanning between about 90-180° aroundthe flow distributor, where the internal manifold is a cavity in theflow distributor through which fluid may flow, (ii) one or more inletsfor delivering fluid from a fluid supply line to the internal manifold,and (iii) an outlet manifold spanning between about 90-180° around theflow distributor, and positioned opposite the internal manifold.

The apparatus may also include a plurality of fins positioned in thecavity that operate to direct fluid to flow in a substantially linearflow pattern from the internal manifold to the outlet manifold. Further,the apparatus may include a rinsing element designed or configured todeliver rinsing fluid to the surface of the substrate. In some cases therinsing element may be designed or configured to be used in the removalcell. In other cases, the rinsing element may be positioned in a modulethat is separate from the removal cell, such as a spin rinse dryingmodule. The substrate to be treated may have a diameter of 300 or 450 mmin certain cases. The internal manifold of the apparatus may include aplurality of showerhead outlet holes designed or configured to deliverfluid to the cavity. In some implementations, the showerhead outletholes are positioned between the substrate holder and the base plate andradially outside of the peripheral edge of the substrate. The apparatusalso may include a gap between the flow distributor and the substrateholder. In various cases, this gap is between about 0.25-8 mm. In someembodiments, the internal manifold includes a plurality of angularlydistinct sections. In a particular implementation, the flow to at leastone angularly distinct section of the internal manifold may becontrolled independently of at least one other angularly distinctsection of the internal manifold.

These and other features will be described below with reference to theassociated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a flowchart showing various operations in a typical WLPprocess sequence.

FIG. 1B illustrates a substrate at the various stages described in FIG.1A

FIG. 2 shows a photoresist stripping operation in accordance with theembodiments herein.

FIG. 3 illustrates a simplified cross-sectional view of a removal celland its associated fluid loop.

FIG. 4 shows a simplified cross-sectional view of a removal cell with asubstrate holder in a rinsing position.

FIG. 5 shows a top-down view of a flow distributor according to anembodiment herein.

FIG. 6 illustrates an inlet manifold having six separate sub-regions.

FIG. 7 shows a close-up cross-sectional view of the inlet side of theflow distributor engaged with other components of the apparatus,according to an embodiment herein.

FIG. 8 shows an additional embodiment of the removal apparatus havingprotuberances extending from the base plate towards the wafer.

FIG. 9 shows cross-sectional views of various possible protuberanceshapes.

FIGS. 10A-C show top-down views of various possible protuberance layoutson the base plate.

FIG. 11 shows a perspective view of an exemplary substrate holderaccording to various embodiments herein.

FIG. 12 shows a close up view of an embodiment of a substrate holderengaging a substrate.

FIG. 13 shows a top down view of a cup that may be used in certainimplementations of a substrate holder.

FIG. 14 illustrates a clamshell-type substrate holder engaging asubstrate in a processing chamber.

FIG. 15 is a top-down simplified view of a multi-tool semiconductorprocessing apparatus according to an embodiment disclosed herein.

FIG. 16 is a top-down simplified view of an alternative multi-toolsemiconductor processing apparatus according to an embodiment disclosedherein.

DETAILED DESCRIPTION

In this application, the terms “semiconductor wafer,” “wafer,”“substrate,” “wafer substrate,” and “partially fabricated integratedcircuit” are used interchangeably. One of ordinary skill in the artwould understand that the term “partially fabricated integrated circuit”can refer to a silicon wafer during any of many stages of integratedcircuit fabrication thereon. A wafer or substrate used in thesemiconductor device industry typically has a diameter of 200 mm, or 300mm, or 450 mm. Further, the terms “photoresist” and “resist” are usedinterchangeably. The following detailed description assumes theinvention is implemented on a wafer. However, the invention is not solimited. The work piece may be of various shapes, sizes, and materials.In addition to semiconductor wafers, other work pieces that may takeadvantage of this invention include various articles such as printedcircuit boards and the like.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the presented embodiments.The disclosed embodiments may be practiced without some or all of thesespecific details. In other instances, well-known process operations havenot been described in detail to not unnecessarily obscure the disclosedembodiments. While the disclosed embodiments will be described inconjunction with the specific embodiments, it will be understood that itis not intended to limit the disclosed embodiments.

Further, in the following discussion, when referring to top and bottomfeatures or elements of the disclosed embodiments, the terms top andbottom are simply used for convenience and represent only a single frameof reference or implementation of the invention. Other configurationsare possible, such as those in which the top and bottom components arereversed with respect to gravity and/or the top and bottom componentsbecome the left and right or right and left components. Similarly, theterms horizontal and vertical apply to the embodiments as described andshown in the figures, but it is to be understood that other orientationsare possible.

The embodiments herein are often described in relation to removingnegative photoresist, though the embodiments are not so limited and maybe implemented in a variety of removal/cleaning processes. For example,the methods and apparatus described herein may be used to remove bothnegative and positive photoresist materials. Further, the disclosedtechniques may be implemented to remove other, non-photoresist materialsfrom substrates such as disc-shaped substrates, with the substitution ofappropriate chemistries for removing the target material.

Conventional photoresist stripping methods were originally designedmainly to remove positive photoresist materials that readily dissolve inacetone. These conventional methods often employ soak tanks with N₂bubbling or single-wafer spin systems. Negative resists are oftenremoved with DMSO- or TMAH-based solutions, though other strippingsolutions may be used as well. Unlike positive resists, negative resistsdo not readily dissolve in stripping solution. Instead, the negativeresist tends to swell, lift (i.e., de-laminate), and then partiallydissolve over a relatively long duration. In commercial applications,this dissolution happens over a period of roughly 5 minutes. For smallerscale laboratory-based applications, this dissolution happens over aperiod of roughly 30 minutes.

Certain feature types can exacerbate the difficulty of negativephotoresist removal. For example, in SnAg mushroom plating, where SnAgmaterial is plated to fill and then overfill a feature (thereby creatinga mushroom shape), the SnAg overfill can pin a certain amount ofphotoresist material under the top portion of the mushroom-shapeddeposit. This pinned in material is physically challenging to remove.Another example where the feature type affects photoresist removal is inthe case of high pitch (densely packed) features such as bumps andpillars. These high pitch features make it difficult for stripping fluidto penetrate and circulate as needed to remove the photoresist. Theembodiments herein may be used to remove photoresist and othermaterials, even where these difficult geometries are present. In someimplementations, the substrate to be stripped includes features having aprincipal dimension between about 5-120 μm, for example 20-50 μm. Insome implementations, the substrate to be stripped includes featureshaving a pitch of at most about 250 μm, e.g., between about 5 μm and 100μm. In one embodiment, the substrate to be stripped includes pillars orother structures that are approximately 20×20 μm with a 40 μm pitch. Inanother embodiment, the substrate includes approximately 80×120 μmplated bumps with an approximately 150 μm pitch.

The methods and apparatus disclosed herein provide new techniques forremoving photoresist (and other) materials. The disclosed techniquesprovide for faster, more efficient, and more effective removal ofnegative photoresist.

Methods

FIGS. 1A-1B illustrate different operations undertaken in a typical WLPprocess sequence. In these figures, the photoresist stripping operationis treated at a very high level. FIG. 2 and the accompanying discussiondescribe the photoresist stripping operation in more detail.

FIG. 1A shows a flowchart for a typical WLP process sequence, and FIG.1B shows simplified drawings of a partially fabricated semiconductorsubstrate at each stage described in FIG. 1A. The process 100 may beused for, e.g., forming a WLP structure containing a solder structure,such as a solder ball, and a copper containing structure, such as acopper RDL (redistribution layer) pad, copper pillar, or other similarstructure. The solder ball may be formed from any suitable material suchas a tin containing material such as tin-silver or tin-lead. Other WLPstructures may contain nickel, gold, etc. Any of these materials may bedeposited by electroplating on a substrate containing patternedphotoresist. The copper containing structure may be configured todeliver current between one or more ports and one or more solderstructures in an integrated circuit package. In certain embodiments, thethickness of the copper containing structure can be greater than about 1μm, such as between about 5 μm and about 10 μm, or between about 10 μmand about 30 μm. The thickness is typically the distance between thesubstrate on which copper is plated and the surface of the plated copperwhich interfaces with the solder.

The process 100 begins at step 105, where a seed layer 154 (e.g., acopper seed layer) is deposited on a substrate 150. Deposition of theseed layer 154 in step 105 may occur by physical vapor deposition (PVD).In some embodiments, the seed layer 154 may be deposited on a barrierlayer 152, such as a layer of tantalum (Ta) or tantalum nitride (TaN),or a bi-layer of TaN/Ta.

The process 100 continues at step 110, where photoresist 156 isdeposited and patterned on the seed layer 154. In some embodiments, thephotoresist 156 is deposited by any suitable technique, such as spincoating, and then patterned according to a desired copper RDL and/orsolder bump layout. For example, the photoresist 156 can be patterned byselectively masking, exposing, developing, and etching the photoresist156. Patterning may remove some or all of the barrier layer 152, ifpresent, at ports on the substrate such as I/O ports on an integratedcircuit (not shown).

The process 100 continues at step 115, where material iselectrodeposited on the substrate to form the deposited structure. Incertain implementations, the material deposited is copper, and thedeposited structure is a copper-containing structure. In someembodiments, the copper can be plated on the substrate electrolyticallyby immersing the substrate in an electroplating bath and applyingcathodic current to substrate. Alternatively or subsequently, a solderbump may be electroplated in the regions of the substrate where thephotoresist has been removed. In some cases, the solder bump is formedfrom tin and silver. Where the material being deposited is copper, theelectroplating bath can contain positive ions of copper and associatedanions in an acid solution. The source of copper ions may be coppersulfate (CuSO₄), copper methane sulfonate (Cu(CH₃SO₃)₂), coppergluconate (C₁₂H₂₂CuO₁₄), copper sulfamate, copper nitrate, copperphosphate, copper chloride and others. In particular implementations,the electroplating bath may contain between about 10 g/L and about 200g/L of sulfuric acid, and between about 10 g/L and about 80 g/L ofcopper ions. For example, the electroplating bath can include about 140g/L of sulfuric acid and about 40 g/L of copper ions. These exampleelectrolyte formulations are exemplary in nature and are not intended tobe limiting in any way. Where materials other than copper are deposited,the electrolyte will contain the appropriate materials for suchdeposition, as understood by those of ordinary skill in the art.

Step 115 of FIGS. 1A-1B may involve a series of electrofillingprocesses. For example, in the embodiment of FIG. 1B, three layers ofmaterial are deposited. Copper layer 158 is deposited directly on theseed layer 154. Next, an intermediate layer of nickel 160 is optionallyplated on top of the copper layer. This intermediate nickel layer 160may serve as a diffusion barrier layer. The copper layer 158 and nickellayer 160 together form the deposited structure described herein. Thethird layer deposited during step 115 in the embodiment of FIG. 1B is atin-silver solder layer 162. In certain cases, the solder material isnot electroplated during this step, but is instead introduced at a laterstep in the process, as will be described in more detail below.

Another example series of electrofilling processes that may be involvedin step 115 is described in U.S. Pat. No. 6,793,796, filed Feb. 28, 2001(attorney docket no. NOVLP073), the entirety of which is herebyincorporated by reference. The description recites at least four phasesof the electrofilling process and discloses controlled current densitymethods for each phase for optimal filling of relatively small recessedfeatures.

The process 100 continues at step 120 where the photoresist 156 isremoved from the substrate. The photoresist 156 may be stripped orotherwise removed from the substrate using the techniques describedbelow (though of course other techniques are possible). Once thephotoresist 156 is removed, portions of the seed layer 154 and anybarrier layer 152 may be exposed. In the embodiment shown in FIG. 1B,the copper layer 158 is electrodeposited directly on top of the copperseed layer 154. Therefore, for the purpose of clarity, the seed layer154 and the electrodeposited copper layer 158 are collectively shown ascopper layer 158 from this point on.

The process 100 continues at step 125, where the seed 154 and anybarrier layers 152 are removed. In some embodiments, for example, theseed 154 and/or the barrier layers 152 that were previously protected byphotoresist 156 may be removed by chemical etching.

In certain embodiments, instead of electrodepositing solder material instep 115, solder may be provided at this point in the process. Usingthis method (not shown in FIGS. 1A-1B), a solder structure contacts apad of the deposited structure. In some embodiments, the solderstructure is a solder structure (e.g., a solder ball) that ismechanically dropped or otherwise placed to contact the pad of thedeposited structure. In other embodiments, the solder structure isformed by electrolytically plating solder material onto the pad of thedeposited structure.

Solder structures are used to electrically connect IC packagingstructures to the interconnects of ICs. For example, pads on a coppercontaining structure are designated areas upon which soldering, wirebonding, flip chip mounting, or other similar connection can occur. Insome embodiments, a solder structure can be affixed on top of the pad,which can be flat or elevated.

The solder structure may include an elemental metal or metal alloysolder material that may be joined with another material to form a seal.In some embodiments, the solder structure may include tin or tin alloysolders. For example, the solder structure may include tin, tin-silver,tin-silver-copper, tin-copper, or tin-lead. While tin-lead may providegood quality “bumps” for packaging and are relatively easy to plate,lead may be less desirable than silver because of its toxicity.

In certain embodiments, the solder structure may be a solder ball with adiameter between about 100 μm and about 500 μm. In other embodiments,the solder structure may be a solder layer plated electrolytically indefined portions of the substrate, as described above in relation tostep 115. In certain cases, the solder layer may be between about 10-50μm thick.

Plating of the solder structure can be accomplished using any suitableelectroplating technique known in the art. Plating of solder material,such as binary tin-silver or ternary tin-silver-copper, can beaccomplished using an electroplating bath solution containing ions oftwo different metals as described in U.S. patent application Ser. No.13/305,384, filed Nov. 28, 2011 (attorney docket no. NOVLP368), theentirety of which is herein incorporated by reference.

The process 100 continues at step 130, where liquid flux 152 isdispensed onto the wafer. A spin coater may be used to accomplish thisfluid delivery in certain embodiments. The flux may be used to preventoxidation of the underlying materials and allow solder to flow easily onthe work piece rather than forming beads as may otherwise occur. It isdesirable to prevent oxidation of the underlying material because soldermaterials may attach very well to certain materials and poorly tooxidized forms of those materials. An example is tin-silver solder inthe context of copper and copper oxide. The tin-silver solder attachesvery well to copper, but poorly to copper oxide. Because copper oxidesreadily form at the temperatures used for soldering, the flux is used,in part, to provide a strongly reducing environment (at the elevatedtemperatures used for soldering) to prevent such oxidation of thesurface. In this way, the solder is able to maintain good adhesion tothe underlying copper material.

The process 100 continues at step 135, where the solder structure 162 isreflowed to allow formation of a solder joint with the depositedstructure. In other words, the solder structure is carefully melted orreflowed to facilitate creation of an electrically conductive interfaceattached to the pad of the deposited structure.

FIG. 2 shows a process flowchart for one approach to carrying out thephotoresist strip step 120 of FIG. 1, and will be described withreference to the apparatus shown in FIGS. 3-4. Photoresist strippingprocess 200 begins at step 205 where a photoresist-coated substrate 301is received and sealed in, for example, a substrate holder 302 in aremoval cell 300. The substrate holder 302, sometimes also referred toas a wafer holder, supports the periphery of the substrate in a roughlyring-shaped cup in order to hold the substrate in place. A cone maypress down on the back side of the substrate to help secure it in thecup The substrate 301 is oriented such that the photoresist-coatedsurface faces away from the substrate holder 302. In the embodiment ofFIG. 3, the photoresist-coated surface of the substrate 301 facesdownwards.

While some aspects described herein may be employed in various types ofapparatus, for simplicity and clarity, most of the discussion concernswafer-face-down, “fountain” stripping apparatus. In such apparatus, thework piece to stripped (typically a semiconductor wafer in the examplespresented herein) generally has a substantially horizontal orientation(which may in some cases vary by a few degrees from true horizontal forsome part of, or during the entire stripping process) and is powered torotate during stripping. The fountain stripping apparatus has manydesign features in common with analogous “fountain” plating apparatus.One example of a member of the fountain plating class of cells/apparatusis the Sabre® Electroplating System produced by and available from LamResearch Corporation of Fremont, Calif. Additionally, fountainelectroplating systems are described in, e.g., U.S. Pat. Nos. 6,800,187,filed Aug. 10, 2001 [attorney docket NOVLP020] and U.S. Pat. No.8,308,931, filed Nov. 7, 2008 [attorney docket NOVLP299], which areincorporated herein by reference in their entireties. Though thediscussion herein focuses on this type of horizontal substrateorientation, other orientations are possible. In one example, the wafermay be oriented in a substantially vertical manner.

The photoresist material is typically deposited some distance away fromthe edge of the substrate, e.g., about 1 mm, leaving a strip of metalsubstrate exposed around the periphery of the wafer. The substrateholder 302 seals onto the substrate 301 at this exposed metal region,rather than on the photoresist itself. This arrangement forms a reliableseal and prevents photoresist from being trapped by the substrateholder, which could cause that trapped material to undesirably remain onthe substrate. It is beneficial to seal the substrate in the substrateholder because it helps prevent fluid leakage that may require excessivequantities of stripping chemicals and otherwise cause poor fluiddynamics (e.g., flow that is discontinuous near the edge of the wafer)within the removal cell.

The process 200 continues at step 210, where the substrate 301 isrotated and immersed in heated stripping solution. The rotation maybegin before, during or after immersion. In some embodiments, therotation occurs at a rate between about 1-20 RPM, e.g., between about5-15 RPM. In the embodiment of FIG. 3, the stripping solution fillscavity 306 between the plating face of substrate 301 and a bottom plate304, which are substantially parallel to one another (e.g., within about20°). In some cases, the substrate holder may be positioned in theremoval position (i.e., immersed position) before any fluid enters thecavity 306. In other cases, fluid is provided on the baseplate beforethe substrate holder moves into the removal position. The strippingsolution enters cavity 306 through a flow distributor 308, which will bedescribed in more detail below, and exits cavity 306 through outlet 310.The fluid may flow at a rate between about 20-50 LPM in various cases.The flow distributor 308 includes a C-shaped internal manifold spanninga section of the peripherally located flow distributor. In one example,the internal manifold spans about 120° of the periphery of thesubstrate. This arrangement allows stripping solution to enter cavity306 at one side of the cell, travel across the cavity in a substantiallylinear cross flow pattern, and then exit the cell at outlet 310. Thisproduces a shearing action on the face of the substrate. Because thesubstrate 301 is rotating when it is immersed in stripping solution, thelinear flow patterns are averaged out over the face of the wafer,providing superior material removal results. In other words, by creatinga spatially uniform convective flow field under the wafer and rotatingthe wafer, each feature, and each die exhibits a nearly identical flowpattern over the course of the rotation and the plating process.

At step 215, the substrate is maintained immersed in the strippingsolution for a duration of time. The duration of solution exposure willdepend on various factors including the chemistry involved, thetemperature of the solution, the flow rate of the solution, thethickness and other geometrical characteristics of the photoresist to bestripped, the exact geometry of the removal cell, etc. In a typicalembodiment, the substrate may stay immersed until the photoresist iscompletely or substantially completely removed. In some embodiments,complete removal is achieved in less than about 5 minutes, e.g., lessthan about 4 minutes, less than about 3 minutes, or less than about 2minutes. In some implementations, the material to be removed iscompletely removed. In other implementations, the material issubstantially completely removed (i.e., at least 99% of the material isremoved). In yet other implementations, less of the material may beremoved (e.g., at least 25% of the material, at least 50% of thematerial, at least 75% of the material, or at least 90% of thematerial).

The process 200 then continues at step 220, where the substrate is movedto a rinse position and rinsed, as illustrated in FIG. 4. The rinsingsolution may be provided through a rinsing nozzle 320, which may bemounted to the removal chamber walls 322, or to any other piece of theapparatus, as appropriate. In certain implementations, the nozzle may bestationary, while in other implementations, the nozzle may swing orotherwise move into place as needed. In some embodiments, a plurality ofrinse nozzles may be used. The rinsing solution may be any appropriatesolution, and in certain embodiments is deionized water. The rinsingoperation helps remove stripping solution from the surface of thesubstrate, and also helps remove residual photoresist particles that maybe present. The substrate may then be dried at step 225. In some cases,drying may occur through rotation of the substrate at an elevatedrotation rate (e.g., between about 1000-2000 RPM).

While the rinsing and drying steps 220 and 225 may occur in the removalcell 300, these steps may alternatively occur in separate rinsing and/ordrying modules. These modules may be implemented as part of a multi-toolapparatus.

As shown in FIG. 3, the stripping solution may be provided in arecirculating solution loop. A holding tank 314 may be used to hold areservoir of stripping solution. The holding tank should be sufficientlylarge to hold the necessary amount of solution. The amount of solutionthat is needed will depend on the scale of the substrate/removalchamber/associated plumbing. In a particular embodiment, the holdingtank holds about 50 L of solution.

The holding tank 314 may have a heating element 316, as well astemperature control sensors and feedback loops (not shown), whichoperate to maintain the stripping solution at a desired temperature. Thesolution exits the holding tank 314 and is delivered to pump 318, whichdelivers the fluid to the cross flow inlet 308. When a substrate 301 ispresent and the substrate holder 302 is in the stripping position,narrow cavity 306 forms between the substrate 301 and the bottom plate304. Solution exits the cross flow inlet 308, travels through cavity306, and exits at outlet 310. The solution then flows (in some casesover a weir wall, and in other cases through dedicated plumbing), andpasses through screen 312. In some implementations, the screen 312 isfairly coarse, having openings on the order of about 1 mm, and operatesto remove pieces of photoresist that have fallen off of the substratesurface. The photoresist pieces are typically on the order of acentimeter or a few centimeters. The screen 312 may be located atvarious positions in the flow loop. In some cases the screen 312 may bea separate element through which the fluid passes before reaching theholding tank 314. This embodiment is shown in FIG. 3. In other cases,the screen 312 may be incorporated into the holding tank 314. In somecases, a filter is used instead of a screen.

The screen 312 should be periodically cleaned to remove the unwantedphotoresist or other material. The screen itself generally providessufficient cleaning of the stripping solution. However, the solutionshould be periodically changed, or operated under a bleed-and-feedcycle, in order to provide fresh stripping solution as needed.

Apparatus

The methods described herein may be performed by any suitable apparatushaving a material removal module as described herein. A suitableapparatus typically includes a system controller having instructions forcontrolling process operations associated with photoresist stripping orother removal operation and optionally other operations. In someembodiments, the hardware may include one or more process stationsincluded in a process tool or platform.

Some of the embodiments herein relate to removal cells. Certain aspectsof these removal cells have been described or mentioned above, and willbe more fully described in this section.

A typical removal cell in accordance with the embodiments herein willinclude a removal chamber having a wafer holder and a flow distributor.The flow distributor may include, among other elements, a base plate(sometimes referred to as a bottom plate), a fluid inlet and a fluidoutlet. The fluid inlet may include an internal manifold and ashowerhead. The removal cell is also typically associated with asolution holding tank, a screen or other filter, a heater, and a pump influidic communication with the removal cell. The overall arrangement ofthese elements is shown in FIG. 3.

FIG. 5 shows a top down view of a flow distributor 500. The flowdistributor 500 is typically located at least partially peripherallyoutside the substrate, and at least partially below the plane of thesubstrate. As noted above, the flow distributor 500 may include multipleelements including an inlet 504, flow directional fins 508, and outlet510. In certain embodiments, the base plate may be implemented as partof the flow distributor, though in other cases the base plate may be aseparate element. The inlet 504, may include multiple elements includingan internal manifold (sometimes referred to as an inlet manifold orcross flow injection manifold) (not visible in FIG. 5) and a manifoldshowerhead 506 having a plurality of showerhead holes 507. Theshowerhead holes 507 are sometimes oriented such that the fluid exitingthe holes is traveling in a direction parallel to the face of thesubstrate. In other cases, the showerhead holes 507 are oriented suchthat the fluid exiting the holes initially travels upward toward theplating face of the substrate. Typically, when the showerhead holes 507are oriented in the latter fashion, the flow direction is changed from(a) towards the substrate to (b) parallel to the substrate, oftenthrough interaction with an element of the flow distributor (e.g., theflow may change direction after encountering a surface of the flowdistributor).

In some embodiments, the internal manifold forms a continuousfluidically coupled cavity within the flow distributor 500. In this casethe cross flow feed channel(s) exit into one continuous and connectedinternal manifold chamber. In other embodiments, the internal manifoldis divided into angularly distinct and completely or partially separatedsegments. The flow to each segment may be independently controlled insome cases. In a specific embodiment, each of these angularly distinctsegments is fluidly coupled to a separate feed channel 503 disposed inthe flow distributor 500. In some cases, flow constricting rods may beplaced in the fluid inlet paths to help control the flow of fluiddelivered to each segment of the inlet. The internalmanifold/inlet/showerhead sub-regions are illustrated in FIG. 6. Incertain embodiments, each of these distinct sub-regions of the internalmanifold has the same volume and/or the same angular extent. Similarly,the outlet may be divided into angularly distinct sub-regions in thesame manner as the inlet. As such, the teachings herein regardingmulti-section inlets also apply to multi-section outlets.

The number of individual inlet channels and sub-regions may be betweenabout 1-12, for example between about 4-6. In one embodiment, there are6 inlet channels, as shown in FIG. 5. The solution inlet may be dividedinto a plurality of inlets in order to provide uniform linear flow overthe face of the wafer. If the inlet were not divided, there would be apressure differential between angularly distinct fluid entry points,causing the fluid to flow across the face of the substrate at differentvelocities, thereby forming a less uniform flow pattern. The inletchannels 503 feed the internal manifold, which then feeds showerhead 506of inlet 504.

The internal manifold is an azimuthal cavity which may be a dug outchannel within the flow distributor 500 that can distribute the fluidfrom the various individual feed channels 503 to the various multipleflow distribution holes 507 of the cross flow showerhead plate 506. Thisinternal manifold (and the associated inlet 504) is located along anangular section of the peripheral or edge region of the flow distributor500, which is positioned around and slightly outside the periphery ofthe substrate when engaged. In some cases, the internal manifold andinlet 504 span a section that is between about 90-180° (e.g., betweenabout 120-170°, or between about)140-150° around the periphery of thesubstrate. In a particular case, the internal manifold and inlet spanabout 120° around the periphery of the substrate. The showerhead 506 mayspan these same angular extents.

As shown in more detail in FIG. 7, the internal manifold 704 may have an“L-shaped” cross section, where the manifold extends both (a) up theperipheral outside vertical surface of substrate holder 702, as well as(b) under the horizontal bottom surface of the substrate holder 702. Thetaller outer part of the manifold may be between about 5-20 mm tall, forexample between about 10-15 mm tall, and in one embodiment is about 8.5mm tall. The length of the taller section of the internal manifold (asmeasured in a horizontal radial direction in the embodiment of FIG. 7)may be between about 5-20 mm in a number of cases, and in one embodimentis about 15 mm long. In some embodiments, the shorter inner part of theinternal manifold may be between about 2-10 mm tall, for example betweenabout 4-6 mm tall, and in one embodiment is about 2.5 mm tall. Theshorter inner part of the manifold may have a length that is betweenabout 2-10 mm long, for example between about 4-6 mm long, and in oneembodiment is about 6 mm long.

The internal manifold 704 and associated showerhead 706 extendhorizontally partially under the substrate holder 702. While it isfeasible for the showerhead 706 to extend all the way to the innerbottom corner of the substrate holder 702, it may be desirable toterminate the showerhead 706 under the substrate holder 702 such thatthere is some distance 715 between the showerhead holes 707 and thiscorner of the substrate holder 702. This separation distance 715 may bebeneficial because it helps ensure that the flow is more established anduniform when it flows over the face of the substrate 701. In someembodiments, the distance 715 may be between about 2-30 mm, for examplebetween about 10-15 mm. Without such distance 715, the edge of the wafercould experience certain non-uniformities due to the initial flowconditions out of showerhead holes 707.

In the depicted embodiment, there is a small gap (e.g., between about0.25-2.5 mm across) between the internal manifold 704 and the waferholder 702. The horizontally oriented gap may have the same or differentgap distance than the vertically oriented gap. In certainimplementations, the vertically oriented gap has a width between about0.5-8 mm. In these or other implementations, the horizontally orientedgap has a height between about 0.25-8 mm. In one embodiment, thehorizontally oriented gap under the substrate holder 702 is about 0.5 mmtall, and the vertically oriented gap outside the substrate holder 702is about 2 mm wide. These narrow gaps prevent fluid leakage, therebypromoting desirable hydrodynamic conditions over the face of the wafer701. Further, the outer/tall portion of the internal manifold 704 mayhelp to establish uniform flow patterns over the face of the wafer bycreating a larger reservoir from which fluid is delivered to themanifold showerhead 706.

In certain other embodiments (not shown), the internal manifold may beflat instead of L-shaped. In these embodiments, there may be anotherresistance-inducing element near the bottom of the substrate holder. Theresistance inducing element may be anything which restricts the flow offluid in areas outside of the cavity between the substrate 701 and baseplate 714. In one example, the additional resistance inducing element isa block of material that partially extends up the outer wall of thesubstrate holder 702, analogous to the tall part of the internalmanifold 704 shown in FIG. 7. In another example, a seal (e.g., aflexible seal) is positioned between the substrate holder 702 and somepart of the flow distributor 708 (e.g., the internal manifold 704,showerhead 706, etc.). The use of a seal may be less desirable in termsof apparatus degradation and replacement costs than the otherembodiments disclosed herein. Regardless of the geometry of the internalmanifold 704, fluid is provided to the manifold 704 through inlet(s)703.

Returning to FIG. 5, the outlet of the internal manifold 504 is referredto as a manifold showerhead 506. Stripping solution is fed into theshowerhead 506 and exits through a plurality of small holes 507 that aredirected parallel to the wafer plane and base plate. The use of a largenumber of holes is advantageous in producing a uniform flow over thesurface of the wafer. In some embodiments, the manifold showerhead 506includes between about 100-200 individual holes 507. In the embodimentof FIG. 5, the showerhead holes 507 may not be drawn to scale. Therewill typically be more than 6 holes 507 between each pair of directionalfins 508, though this is not necessarily always the case.

After the solution exits the showerhead holes 507, the flow is directedby a plurality of flow directional fins 508, which may be implemented aspart of the flow distributor 500 or as separate elements. The number offins 508 near each of the inlet and outlet sides of the flow distributor500 may range from about 2-30. In some cases, more than 30 fins areused. The directional fins 508 define largely segregated fluid passagesunder a surface of the substrate holder and between adjacent directionalfins 508. In some cases, the purpose of the fins is to redirect andconfine flow exiting from the manifold showerhead holes 507 from anotherwise radially inward direction to a “left to right” flow trajectory(left being the inlet side of the cross flow, right being the outletside). The solution exiting the holes 507 of the manifold showerhead 506is directed by the directional fins 508 along a flow streamline causedby the orientation of the directional fins 508. In certain embodiments,all the directional fins 508 of the flow distributor are parallel to oneanother, as shown in FIG. 5. This helps to establish a uniform crossflow direction within the internal manifold. In various embodiments, thedirectional fins 508 are disposed both along the inlet and outlet sideof the flow distributor 508, as shown in FIG. 5.

Returning to FIG. 7, after solution exits the manifold showerhead 706through showerhead holes 707, it enters cavity 716 defined on the top bythe substrate 701 (note that around the very edge, cavity 716 is definedon the top by the bottom surface of the substrate holder rather than thesubstrate itself) and on the bottom by base plate 714. This cavity 716is substrate-shaped (e.g., disc-shaped) and extends under the exposedsurface of the substrate. The diameter of the cavity is slightly largerthan the diameter of the work piece, and in certain cases these twodiameters are practically identical. In various implementations, theheight of the cavity 716 is between about 2-15 mm, e.g., 8-10 mm. Thisheight is fairly short to promote shearing of the substrate face byimparting a high cross-flow rate through the cavity 716. This high flowrate through a narrow cavity may promote more turbulent flow near theface of the wafer, which is beneficial in terms of materialremoval/cleaning results. The flow directional fins shown in FIG. 5 arelocated in cavity 716.

The embodiment of FIG. 7 shows a step in cavity 716 where it extendsaround the corner of the substrate holder, though this step is notpresent in all embodiments. In certain cases, the peripheral bottomsurface of wafer holder 702 may be angled such that there is a slopebetween the showerhead holes 707 and the edge of the substrate 701.Where a step is present, it should be minimal in height (i.e., the stepshould be very short in the direction perpendicular to the substrate).This short step height helps ensure that the height of cavity 716remains small, promoting favorable hydrodynamic conditions over the faceof the substrate 701. In order to achieve a small step, the substrateholder should have a very thin bottom thickness (e.g., less than about 5mm, less than about 3 mm, or less than about 1.5 mm).

After the solution passes through cavity 716, it exits through an outletmanifold (not shown) in the flow distributor 708. The outlet manifoldmay span between a section that is between about 90-180° (e.g., betweenabout 120-170°, or between about)140-150° around the periphery of thesubstrate. In a particular case, the outlet manifold spans about 120°around the periphery of the substrate.

FIG. 8 shows an alternative embodiment having a plurality ofprotuberances 820 located in the cavity 816 between the substrate 801and the base plate 814 and oriented perpendicular to the cross flowacross the substrate 801. The protuberances modify a flow field adjacentto the wafer to increase mass transfer to the wafer and improve theuniformity of the mass transfer over the face of the wafer. This may beaccomplished by increasing the local Reynolds number (Re) of the fluidadjacent to the surface of the wafer, and providing a more uniform crossflow over the surface of the wafer.

The protuberances may be provided as relatively long, thin shapes thatoperate to promote significantly higher flow velocities through cavity814, thereby achieving improved fluid dynamics for material removal. Inother words, the protuberances create localized turbulent zones near andon the surface of the wafer.

FIG. 9 shows various possible embodiments of protuberance shapes. Theseshapes are intended to be illustrative and not limiting, and one havingordinary skill in the art would recognize that various protuberanceshapes, sizes and orientations are contemplated to be within the scopeof the invention. The protuberances are typically thin and long, and areoriented perpendicular to the direction of the cross flow. Theprotuberances may be normal to the base plate surface or may be angled.They may be rectangular, triangular, cylindrical, some combinationthereof, or a different shape. In certain implementations theprotuberances may have holes to further affect the flow of platingsolution. The protuberances may be continuous or discontinuous alongtheir length. In some cases the protuberances may extend across theentire face of the base plate. In other cases the peripheral edge regionof the base plate is free of protuberances.

In some embodiments, the protuberances may be of varying shapes and/orsizes (for example, alternating rectangular and triangularprotuberances). Certain shapes may have fluidic advantages, for example,a rectangular protuberance with a triangular tip may result in greatershear of the fluid and/or a higher propensity of forming vortices withinthe stripping solution.

In some embodiments, the protuberance height is between about 30-85% ofthe distance between the base plate and wafer surface. For example, ifthe distance between the base plate and wafer is 6 mm, the height of theprotuberances should be between about 2-5 mm, for example between about2-4 mm. Another way to characterize the protuberance height is byspecifying the distance between the substrate surface and the top of theprotuberance(s). In many implementations, this distance is between about1 and 4 mm. For example, if the gap between the base plate and wafersurface is 10 mm and the tops of the protuberances are about 1 to 4millimeters away from the surface of the wafer, this means that theprotuberances are about 6 to 9 millimeters tall (10−4 mm=6 mm, to 10−1mm=9 mm). The maximum height of the protuberance may be limited bycertain flow characteristics in the system.

The protuberance should be tall enough such that it is able to induce aturbulent flow (e.g., Re>1400) in the base plate to wafer channel. Theprotuberances allow the stripping solution to penetrate between featuresmore easily due to the increased turbulent flow near the wafer.

The width of the protuberances may be between about 0.5-3 mm (e.g.,between about 1-2 mm). The length of the protuberance may be up to thelength of the substrate chord on which the protuberance is positioned.In the center of the substrate, the maximum protuberance length is thediameter of the substrate. In areas away from the center of thesubstrate, this maximum length will be some lesser distance. Shorterprotuberances may also be used. The distance between the protuberancesmay be between about 2-10 millimeters. This distance may be constant orvariable between different sets of protuberances.

The layout of the protuberances may be systematic or random. Variouspossible protuberance layouts are presented in FIGS. 10A-C. For each ofthese figures, the fluid flow is in a left-to-right direction, asindicated by the arrow in the panel of FIG. 10A. In this embodiment, theprotuberances extend length-wise over the entire or substantially entirelength of the base plate. The protuberances are oriented parallel to oneanother and perpendicular to the direction of cross flow. In FIG. 10B,the protuberances are arranged in a set-off manner such that channelsbetween the protuberances do not line up with each other in thedirection of cross flow. In this embodiment the protuberances may beconsidered discontinuous in the length-wise direction. In FIG. 10C, theprotuberances are arranged more randomly, having substantially varyingprotuberance lengths, as well as varying distances between adjacentprotuberances.

In some embodiments, megasonic or ultrasonic energy is delivered to thesubstrate surface. In some implementations, a MegPie transducer (notshown) is coupled to the base plate. The MegPie delivers megasonicenergy to the base plate, which is transferred to the strippingsolution. This megasonic energy helps remove the photoresist or othermaterial from the face of the substrate.

FIG. 11 shows a perspective view of an exemplary substrate holder 100.This substrate holder may be used in connection with various types ofsemiconductor processing apparatus, including both removal cells anddeposition cells. The focus in the following discussion will be onremoval cells. The apparatus 100 includes wafer-engaging components,which are sometimes referred to as “clamshell” components, a “clamshell”assembly, or a “clamshell.” The clamshell assembly comprises a cup 101and a cone 103. As will be shown in FIG. 12, the cup 101 holds a wafer,and the cone 103 clamps the wafer securely in the cup. Other cup andcone designs beyond those specifically depicted here can be used. Acommon feature is a cup that has an interior region in which the waferresides and a cone that presses the wafer against the cup to hold it inplace. The bottom of the cup should have a relatively thin thickness(e.g., less than about 5 mm) in order to maintain a narrow gap betweenthe surface of the wafer and the base plate. The cup may be sized toengage with wafers of various diameters; e.g., wafers of diameter, 200mm, 300 mm, or 450 mm.

In the depicted embodiment, the clamshell assembly (the cup 101 and thecone 103) is supported by struts 104, which are connected to a top plate105. This assembly (101, 103, 104, and 105) is driven by a motor 107 viaa spindle 106 connected to the top plate 105. The motor 107 is attachedto a mounting bracket (not shown). The spindle 106 transmits torque(from the motor 107) to the clamshell assembly causing rotation of awafer (not shown in this figure) held therein during stripping. An aircylinder (not shown) within the spindle 106 also provides a verticalforce for engaging the cup 101 with the cone 103. When the clamshell isdisengaged (not shown), a robot with an end effector arm can insert awafer in between the cup 101 and the cone 103. After a wafer isinserted, the cone 103 is engaged with the cup 101, which immobilizesthe wafer within apparatus 100 leaving only the wafer front side (worksurface) exposed to solution.

In certain embodiments, the clamshell includes a spray skirt 109 thatprotects the cone 103 from splashing solution. In the depictedembodiment, the spray skirt 109 includes a vertical circumferentialsleeve and a circular cap portion. A spacing member 110 maintainsseparation between the spray skirt 109 and the cone 103.

For the purposes of this discussion, the assembly including components101-110 is collectively referred to as a “wafer holder” 111. Notehowever, that the concept of a “wafer holder” or “substrate holder”extends generally to various combinations and sub-combinations ofcomponents that engage a wafer and allow its movement and positioning.

Further, the entire wafer holder 111 is lifted vertically either up ordown to immerse the proximal end of wafer holder into a strippingsolution (or plating solution) via an actuator (not shown). Thus, atwo-component positioning mechanism provides both vertical movementalong a trajectory perpendicular to a solution surface and a tiltingmovement allowing deviation from a horizontal orientation (i.e.,parallel to the solution surface) for the wafer (angled-wafer immersioncapability).

FIG. 12 shows a close up view of an embodiment of a substrate holderengaging a substrate 304. The closing operation involves lowering a cup308 and pressing with the cup 308 onto the back side of the wafer 304.As a result of this pressure, the active surface 306 comes into thecontact with the lip 212 b of the lipseal 212. The compression alsoensures that the entire perimeter of the lip 212 b is in the contactwith front surface 306, especially if there are some imperfections insurfaces of either one. A lipseal 212 is typically made out ofcompressible materials.

The clamshell assembly shown in FIG. 12 may be used in accordance withthe present embodiments (both in removal cells and in plating cells),and in various cases may be implemented on a Sabre® electroplatingsystem supplied by Lam Research Corporation of Fremont, Calif.Implementation of the illustrated clamshell assembly improves sealingand helps protect the substrate and apparatus. It is also permits easymanual cleaning and as well as automatic cleaning, rinsing andcleaning/etching operations (known as cup contact rinse, CCR andautomatic contact etch, ACE operations). FIG. 13 shows an embodiment ofa clamshell cup 410, which may be implemented as part of the substrateholder. The clamshell 410 includes the elastomeric lipseal 418, whichforms a fluid-tight seal around its inner edge.

FIG. 14 shows a schematic representation of a typical clamshell assemblythat may be used in certain embodiments (e.g., in a removal cell and/orin a plating cell). The apparatus 1300 may have a motor 107 for rotatingthe clamshell (elements 202, 204, 210, 212, 214, 306, 308 and other) anda shaft 106 with an air cylinder for lifting a cone 308 inside theapparatus. The motor 107 and the shaft 106 are further described in thecontext of FIG. 11. Operations of the motor 107 and the air cylinder maybe controlled by a system controller 1302. In certain embodiments, asystem controller 1302 is employed to control process conditions duringmaterial stripping (e.g., photoresist stripping, copper or othermaterial deposition, insertion and removal of wafers, etc. Thecontroller 1302 may include one or more memory devices and one or moreprocessors with a CPU or computer, analog and/or digital input/outputconnections, stepper motor controller boards, etc., and will bedescribed in further detail below.

FIG. 15 shows an exemplary multi-tool apparatus that may be used toimplement the embodiments herein. The electrodeposition apparatus 900can include three separate electroplating modules 902, 904, and 906. Theelectrodeposition apparatus 900 can also include a stripping module 916.Further, two separate modules 912 and 914 may be configured for variousprocess operations. For example, in some embodiments, one or more ofmodules 912 and 914 may be a spin rinse drying (SRD) module. In otherembodiments, one or more of the modules 912 and 914 may bepost-electrofill modules (PEMs), each configured to perform a function,such as edge bevel removal, backside etching, and acid cleaning ofsubstrates after they have been processed by one of the electroplatingmodules 902, 904, and 906.

The electrodeposition apparatus 900 includes a central electrodepositionchamber 924. The central electrodeposition chamber 924 is a chamber thatholds the chemical solution used as the electroplating solution in theelectroplating modules 902, 904, and 906. The electrodepositionapparatus 900 also includes a dosing system 926 that may store anddeliver additives for the electroplating solution. A chemical dilutionmodule 922 may store and mix chemicals to be used as an etchant. Afiltration and pumping unit 928 may filter the electroplating solutionfor the central electrodeposition chamber 924 and pump it to theelectroplating modules.

A system controller 930 provides electronic and interface controlsrequired to operate the electrodeposition apparatus 900. The systemcontroller 930 (which may include one or more physical or logicalcontrollers) controls some or all of the properties of theelectroplating apparatus 900. The system controller 930 typicallyincludes one or more memory devices and one or more processors. Theprocessor may include a central processing unit (CPU) or computer,analog and/or digital input/output connections, stepper motor controllerboards, and other like components. Instructions for implementingappropriate control operations as described herein may be executed onthe processor. These instructions may be stored on the memory devicesassociated with the system controller 930 or they may be provided over anetwork. In certain embodiments, the system controller 930 executessystem control software.

The system control software in the electrodeposition apparatus 900 mayinclude instructions for controlling the timing, mixture of electrolytecomponents (including the concentration of one or more electrolytecomponents), inlet pressure, plating cell pressure, plating celltemperature, mixture of stripping solution components, removal celltemperature, removal cell pressure, substrate temperature, current andpotential applied to the substrate and any other electrodes, substrateposition, substrate rotation, and other parameters of a particularprocess performed by the electrodeposition apparatus 900.

System control logic may be configured in any suitable way. For example,various process tool component sub-routines or control objects may bewritten to control operation of the process tool components necessary tocarry out various process tool processes. System control software may becoded in any suitable computer readable programming language. The logicmay also be implemented as hardware in a programmable logic device(e.g., an FPGA), an ASIC, or other appropriate vehicle.

In some embodiments, system control logic includes input/output control(IOC) sequencing instructions for controlling the various parametersdescribed above. For example, each phase of an electroplating processmay include one or more instructions for execution by the systemcontroller 930. The instructions for setting process conditions for animmersion process phase may be included in a corresponding immersionrecipe phase. In some embodiments, the electroplating recipe phases maybe sequentially arranged, so that all instructions for an electroplatingprocess phase are executed concurrently with that process phase.

The control logic may be divided into various components such asprograms or sections of programs in some embodiments. Examples of logiccomponents for this purpose include a substrate positioning component,an electrolyte composition control component, a stripping solutioncomposition control component, a solution flow control component, apressure control component, a heater control component, and apotential/current power supply control component. The controller mayexecute the substrate positioning component by, for example, directingthe substrate holder to move (rotate, lift, tilt) as desired. Thecontroller may control the composition and flow of various fluids(including but not limited to electrolyte and stripping solution) bydirecting certain valves to open and close at various times duringprocessing. The controller may execute the pressure control program bydirecting certain valves, pumps and/or seals to be open/on orclosed/off. Similarly, the controller may execute the temperaturecontrol program by, for example, directing one or more heating and/orcooling elements to turn on or off. The controller may control the powersupply by directing the power supply to provide desired levels ofcurrent/potential throughout processing.

In some embodiments, there may be a user interface associated with thesystem controller 930. The user interface may include a display screen,graphical software displays of the apparatus and/or process conditions,and user input devices such as pointing devices, keyboards, touchscreens, microphones, etc.

In some embodiments, parameters adjusted by the system controller 930may relate to process conditions. Non-limiting examples include solutionconditions (temperature, composition, and flow rate), substrate position(rotation rate, linear (vertical) speed, angle from horizontal) atvarious stages, etc. These parameters may be provided to the user in theform of a recipe, which may be entered utilizing the user interface.

Signals for monitoring the process may be provided by analog and/ordigital input connections of the system controller 930 from variousprocess tool sensors. The signals for controlling the process may beoutput on the analog and digital output connections of the process tool.Non-limiting examples of process tool sensors that may be monitoredinclude mass flow controllers, pressure sensors (such as manometers),thermocouples, optical position sensors, etc. Appropriately programmedfeedback and control algorithms may be used with data from these sensorsto maintain process conditions.

In one embodiment of a multi-tool apparatus, the instructions caninclude inserting the substrate in a wafer holder, tilting thesubstrate, biasing the substrate during immersion, and electrodepositinga copper containing structure on a substrate. The instructions mayfurther include transferring the substrate to a removal cell, immersingthe substrate in stripping solution, rotating the substrate, flowingstripping solution from an internal cross flow manifold and across theface of the wafer (including adjusting the flow rate, total or a portionthereof), and removing, rinsing and drying the substrate.

A hand-off tool 940 may select a substrate from a substrate cassettesuch as the cassette 942 or the cassette 944. The cassettes 942 or 944may be front opening unified pods (FOUPs). A FOUP is an enclosuredesigned to hold substrates securely and safely in a controlledenvironment and to allow the substrates to be removed for processing ormeasurement by tools equipped with appropriate load ports and robotichandling systems. The hand-off tool 940 may hold the substrate using avacuum attachment or some other attaching mechanism.

The hand-off tool 940 may interface with a wafer handling station 932,the cassettes 942 or 944, a transfer station 950, or an aligner 948.From the transfer station 950, a hand-off tool 946 may gain access tothe substrate. The transfer station 950 may be a slot or a position fromand to which hand-off tools 940 and 946 may pass substrates withoutgoing through the aligner 948. In some embodiments, however, to ensurethat a substrate is properly aligned on the hand-off tool 946 forprecision delivery to an electroplating module, the hand-off tool 946may align the substrate with an aligner 948. The hand-off tool 946 mayalso deliver a substrate to one of the electroplating modules 902, 904,or 906, or to the removal cell 916, or to one of the separate modules912 and 914 configured for various process operations.

An apparatus configured to allow efficient cycling of substrates throughsequential plating, rinsing, drying, and PEM process operations (such asstripping) may be useful for implementations for use in a manufacturingenvironment. To accomplish this, the module 912 can be configured as aspin rinse dryer and an edge bevel removal chamber. With such a module912, the substrate would only need to be transported between theelectroplating module 904 and the module 912 for the copper plating andEBR operations. Similarly, where module 916 is a strippingmodule/removal cell, substrate transfer between stations is relativelyefficient and simple.

FIG. 16 shows an additional example of a multi-tool apparatus that maybe used in implementing the embodiments herein. In this embodiment, theelectrodeposition apparatus 1000 has a set of electroplating cells 1007,each containing an electroplating bath, in a paired or multiple “duet”configuration. In addition to electroplating per se, theelectrodeposition apparatus 1000 may perform a variety of otherelectroplating related processes and sub-steps, such as spin-rinsing,spin-drying, metal and silicon wet etching, electroless deposition,pre-wetting and pre-chemical treating, reducing, annealing, photoresiststripping, and surface pre-activation, for example. Theelectrodeposition apparatus 1000 is shown schematically looking top downin FIG. 10, and only a single level or “floor” is revealed in thefigure, but it is to be readily understood by one having ordinary skillin the art that such an apparatus, e.g. the Lam Research Sabre™ 3D tool,can have two or more levels “stacked” on top of each other, eachpotentially having identical or different types of processing stations.

Referring once again to FIG. 16, the substrates 1006 that are to beelectroplated are generally fed to the electrodeposition apparatus 1000through a front end loading FOUP 1001 and, in this example, are broughtfrom the FOUP to the main substrate processing area of theelectrodeposition apparatus 1000 via a front-end robot 1002 that canretract and move a substrate 1006 driven by a spindle 1003 in multipledimensions from one station to another of the accessible stations—twofront-end accessible stations 1004 and also two front-end accessiblestations 1008 are shown in this example. The front-end accessiblestations 1004 and 1008 may include, for example, pre-treatment stations,and spin rinse drying (SRD) stations. These stations 1004 and 1008 mayalso be removal stations as described herein. Lateral movement fromside-to-side of the front-end robot 1002 is accomplished utilizing robottrack 1002 a. Each of the substrates 1006 may be held by a cup/coneassembly (not shown) driven by a spindle 1003 connected to a motor (notshown), and the motor may be attached to a mounting bracket 1009. Alsoshown in this example are the four “duets” of electroplating cells 1007,for a total of eight electroplating cells 1007. The electroplating cells1007 may be used for electroplating copper for the copper containingstructure and electroplating solder material for the solder structure(among other possible materials). A system controller (not shown) may becoupled to the electrodeposition apparatus 1000 to control some or allof the properties of the electrodeposition apparatus 1000. The systemcontroller may be programmed or otherwise configured to executeinstructions according to processes described earlier herein.

The various hardware and method embodiments described above may be usedin conjunction with lithographic patterning tools or processes, forexample, for the fabrication or manufacture of semiconductor devices,displays, LEDs, photovoltaic panels and the like. Typically, though notnecessarily, such tools/processes will be used or conducted together ina common fabrication facility.

Lithographic patterning of a film typically comprises some or all of thefollowing steps, each step enabled with a number of possible tools: (1)application of photoresist on a workpiece, e.g., a substrate having asilicon nitride film formed thereon, using a spin-on or spray-on tool;(2) curing of photoresist using a hot plate or furnace or other suitablecuring tool; (3) exposing the photoresist to visible or UV or x-raylight with a tool such as a wafer stepper; (4) developing the resist soas to selectively remove resist and thereby pattern it using a tool suchas a wet bench or a spray developer; (5) transferring the resist patterninto an underlying film or workpiece by using a dry or plasma-assistedetching tool; and (6) removing the resist using a tool such as an RF ormicrowave plasma resist stripper. In some embodiments, an ashable hardmask layer (such as an amorphous carbon layer) and another suitable hardmask (such as an antireflective layer) may be deposited prior toapplying the photoresist.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated may beperformed in the sequence illustrated, in other sequences, in parallel,or in some cases omitted. Likewise, the order of the above describedprocesses may be changed.

The subject matter of the present disclosure includes all novel andnonobvious combinations and sub-combinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

1. A method of removing material from a substrate, comprising: (a)receiving a substrate having material for removal thereon; (b)positioning and sealing the substrate in a substrate holder such thatthe material for removal is exposed; (c) positioning the substrateholder in a removal position, thereby forming a gap defined on one sideby the substrate, defined on the opposite side by a base plate, anddefined around the edges by a flow distributor, wherein the gap has adimension between about 2-10 mm as measured in a direction perpendicularto a face of the substrate wherein the flow distributor comprises: (i)an internal manifold spanning between about 90-180° around the flowdistributor, wherein the internal manifold is a cavity in the flowdistributor through which fluid may flow, (ii) one or more inlets fordelivering fluid from one or more fluid supply lines to the internalmanifold, and (iii) an outlet manifold spanning between about 90-180°around the flow distributor, and positioned opposite the internalmanifold; (d) rotating the substrate in the substrate holder; and (e)flowing stripping solution from the one or more inlets, through theinternal manifold, into the gap and over the face of the substrate, andout through the outlet manifold, to thereby remove from the substrate atleast some of the material for removal.
 2. The method of claim 1,wherein sealing the substrate in the substrate holder forms a fluidtight seal between the substrate and the substrate holder.
 3. The methodof claim 1, further comprising: positioning the substrate holder in anopen position such that the substrate may be removed from the substrateholder and removing the substrate.
 4. The method of claim 1, wherein thematerial for removal comprises photoresist material.
 5. The method ofclaim 4, wherein the photoresist material comprises negative photoresistmaterial.
 6. The method of claim 1, wherein the stripping solution isflowed at a rate between about 20-40 LPM.
 7. The method of claim 1,wherein the stripping solution comprises a DMSO- and/or TMAH-basedsolution.
 8. The method of claim 1, wherein the substrate has featuresthereon, and wherein the features have a principal dimension betweenabout 5-120 μm.
 9. The method of claim 1, wherein the material forremoval is substantially completely removed within about 4 minutes afterbeginning to flow the stripping solution over the face of the substrate.10. An apparatus for removing material from a substrate, comprising: aremoval cell comprising: (a) a substrate holder configured to hold androtate a disc-shaped substrate in a substrate plane, (b) a base platepositioned substantially parallel to the substrate plane such that a gapis formed between the base plate and the substrate when the substrate ispresent in the substrate holder, wherein the distance between the baseplate and the substrate in the substrate holder is between about 2-10mm, and (c) a flow distributor at least partially positioned between thebaseplate and substrate holder, comprising: (i) an internal manifoldspanning between about 90-180° around the flow distributor, wherein theinternal manifold is a cavity in the flow distributor through whichfluid may flow, (ii) one or more inlets for delivering fluid from afluid supply line to the internal manifold, and (iii) an outlet manifoldspanning between about 90-180° around the flow distributor, andpositioned opposite the internal manifold.
 11. The apparatus of claim10, further comprising a plurality of fins positioned in the gap thatoperate to direct fluid to flow in a substantially linear flow patternfrom the internal manifold to the outlet manifold.
 12. The apparatus ofclaim 10, further comprising a rinsing element designed or configured todeliver rinsing fluid to the surface of the substrate.
 13. The apparatusof claim 12, wherein the rinsing element is designed or configured to beused in the removal cell.
 14. The apparatus of claim 12, wherein therinsing element is positioned in a spin rinse drying module that isseparate from the removal cell.
 15. The apparatus of claim 10, whereinthe substrate has a diameter of about 300 or 450 mm.
 16. The apparatusof claim 10, wherein the internal manifold comprises a plurality ofshowerhead outlet holes designed or configured to deliver fluid to thegap.
 17. The apparatus of claim 16, wherein the showerhead outlet holesare positioned between the substrate holder and the base plate, andradially outside of the peripheral edge of the substrate.
 18. Theapparatus of claim 10, wherein a gap between the flow distributor andthe substrate holder, when engaged, is between about 0.25-8 mm.
 19. Theapparatus of claim 10, wherein the internal manifold comprises aplurality of angularly distinct sections.
 20. The apparatus of claim 19,wherein the flow to at least one angularly distinct section of theinternal manifold may be controlled independently of at least one otherangularly distinct section of the internal manifold.